Affiliation:
1. 1 City of Vancouver, Development, Buildings & Licensing, 515 W 10th Avenue, Vancouver, BC V5Z 4A8, Canada
Abstract
AbstractCooling towers have been linked to Legionnaires' disease cases and outbreaks. Legionella pneumophila results (from a culture-based method) are presented for 557 cooling towers across the City of Vancouver, Canada for 2021. Results of 10 CFU/mL or greater (defined as exceedances) were reported for 30 cooling towers (5.4%), including six >1,000 CFU/mL, and L. pneumophila serogroup 1 (sg1) was identified in 17 of these cooling towers (out of 28 with serogroup-level analysis). The data indicate highly localised Legionella issues, with exceedances concentrated within 16 facilities, including two hospitals. In the 3 months preceding each cooling tower exceedance, the nearest municipal water sampling station had a free chlorine residual of at least 0.46 mg/L and a temperature of <20 °C. There was not a statistically significant correlation between the L. pneumophila concentration of a cooling tower in exceedance and the municipal water free chlorine residual, temperature, pH, turbidity or conductivity. There was a statistically significant negative correlation between the concentrations of L. pneumophila sg1 and other L. pneumophila serogroups in cooling towers. This unique dataset underscores the pivotal role of building owners and managers in preventing the growth of Legionella bacteria and the value of regulations to verify operations and maintenance practices.
Subject
Infectious Diseases,Microbiology (medical),Public Health, Environmental and Occupational Health,Waste Management and Disposal,Water Science and Technology
Reference41 articles.
1. Barskey A. , LackrajD., TripathiP. S., CooleyL., LeeS., SmithJ. & EdensC.2020Legionnaires’ Disease Surveillance Summary Report, United States 2016–2017. Centers for Disease Control and Prevention, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases. Available from: https://www.cdc.gov/legionella/health-depts/surv-reporting/2016-17-surv-report-508.pdf (accessed 29 May 2022).
2. Rising incidence of Legionnaires’ disease and associated epidemiologic patterns, United States, 1992–2018;Emerging Infectious Diseases,2022
3. Microbial wars: competition in ecological niches and within the microbiome;Microbial Cell,2018
4. A model for autumn outbreaks of Legionnaires’ disease associated with cooling towers, linked to system operation and size;Epidemiology & Infection,1993